Friday, February 27, 2015

Osmosis and Diffusion

Diffusion: movement of a chemical from high concentration to low concentration against a gradient. (energized by kinetic energy of particles bouncing around to get equilibrium)
  • solvent: higher concentration of a chemical in a mixture (called a "solution") (more of)
  • solute: lower concentrated chemical in a mixture (It has been "dissolved" into the solvent. (less of)

Osmosis: solvent is water because it is polar (and only works in water).  Concentrations of chemical will move to get equilibrium (how cells work in attracting water).
  • In osmosis, the solute chemical is too large to leave the membrane (container) and blocks the solvent from escaping
  • Water can go in and out so it is "semi-permeable".
  • Net effect: more water goes in.  Solute goes from hypotonic to hypertonic-why it goes against the gradient.

Hypertonic solutions: higher in concentration of the solute than the  solution

Hypotonic solutions: lower in concentration of a solvent

Chemical goes from hypertonic solution to the hypotonic solution

Tour of the Cell

Prokaryote-no nucleus, Bacteria and Archaebacteria
·         No Nucleus-free floating DNA
·         Cell Membrane
·         Cytosol
·         Ribosomes
Eukaryote-animals, plants, fungus, protists (much larger)
·         Organelles including:
·         Cytoskeleton: structure inside the cell (works like a bridge)-microtubules (compressional support) and microfilaments (tensional support)
·         Nucleus (contains DNA and controls cells, makes proteins and enzymes) & Nucleolus (within nucleus, holds the chromosomes that make ribosomes only & where ribosomes are synthesized)
·         Ribosome (mrNA goes through then tRNA comes and builds proteins on it)
·         Mitochondria-generate energy (ATP); endosymbiotic theory (have own DNA & binary fission)
·         Cell Membrane
·         Cytosol-fluid with solutes
·         Lysosome-digestive enzymes that will break down vesicles or if it pops can kill the cell itself “apoptosis” (suicide)
·         Centrioles: positioning in cell, including positions nucleus & roles in cell division (forms division)
·         Cytoplasm
·         Secretory Vesicle (membrane bound container that moves material i.e. vacuole)
·         Rough Endoplasmic reticulum)-membrane continuous with the nucleus. Rough have mRNA to make proteins & produces membranes.
·         Smooth Endoplasmic reticulum:  produces lipids, cholesterol & detoxification
·         Flagellum
·         Vacuole-large are in plants only; stores water & maintains turgor pressure (cell pressure)
·         Golgi Body:  where proteins are modified (shipping/sorting part of cell)
How things go in and out of cells:
·         Diffusion
·         Osmosis

Nucleic Acids DNA and RNA

DNA-directions that make our genes and tell how to make proteins
RNA-shuttles/worker to make Proteins in ribosome
Nucleotides: building blocks of DNA and RNA.  3 parts
1.       Phosphate group
2.       Pentose sugar (5 carbon)
3.       Nitrogenous base (contains nitrogen)
·         Adenine, Guanine (Purines)
·         Cytosine, Thymine (Pyrimidines)
·         In RNA, it is Uracil not Thymine.
·         Done via. dehydration reaction to form covalent bonds.
·         Hydrogen bonds form between Adenine and Thymine; and Cytosine and Guanine.
DNA is a more stable structure as it is two copies going reverse paired from one another.  RNA is simply one copy opened up through DNA replication.
·         DNA backbone is basically a sugar-phosphate-sugar-phosphate alternating base.
Video game  or simulation of this science:  Build section of RNA (and build it and see how it does).


  • Triglyccerides: 3 fatty acid tails (stores energy in body)
  • Lipases: enzymes that break down triglycerides into energy
  • Phospholipids: cell membrane-two fatty acid tails with a head and a negatively charged phosphate group.  (Tails are uncharged).  These form spheres or “Micelles”.  All cells are phospholipid bi-layers.
  • Cholesterol: maintains fluidity of cell membranes.  It holds fatty-acid tails of phospholipids.  It maintains integrity of cell membranes by inter-locking and over-lapping the phospholipid tails.
  • Hydrocarbons: give energy on the carbon tail of the triglyceride (stuff that burns)
  • Glycerold head and fatty-acid tail
  • Saturated: Hydrogen on the outside-straight line hydrocarbon tail.  Solid at room temperature (worst fat for us).
  • Unsatruated-double bonds between carbons eliminate hydrogen and creates kinks.  Liquid at room temperature.

Why water is required for life to exist.


Water is polar: Oxygen holds its Hydrogen bonds strongly (covalent bond) so much that it polarizes it towards the oxygen (oxygen is highly “electronegative”).
As a molecule whole, Hydrogens are + and O2 are – so a second bond forms between the molecules allowing ice to float—a new lattice.  It also creates a high heat capacity (holds heat) allowing for thermoregulation and a conduit for metabolism to occur.  It dissolves materials as well.  Water is a good solvent because it is polar (having a + and – side on the molecule).  It breaks solutes (NaCl) into its parts.




Covalent Bonds:

Hydrogen Bonds:

Ionic Bonds:




Simulations from the University of Colorado: